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# compression KE question

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1. spring constant is 1220nm^-1.

a ball is shot upwards, weighing 25g.
when spring compressed by 36mm work done is 0.81j, and if epe converted into KE, speed of ball is 8.05 ms^-1.

Question asks for compression of spring needed for ball to leave spring w/twice the speed (16.1ms^-1).

using the KE equation, i found that the KE needed would be 0.81*4, which is 3.24J. However I don't know how you would substitute that back to find the compression needed
2. (Original post by Deathlotus)
spring constant is 1220nm^-1.

a ball is shot upwards, weighing 25g.
when spring compressed by 36mm work done is 0.81j, and if epe converted into KE, speed of ball is 8.05 ms^-1.

Question asks for compression of spring needed for ball to leave spring w/twice the speed (16.1ms^-1).

using the KE equation, i found that the KE needed would be 0.81*4, which is 3.24J. However I don't know how you would substitute that back to find the compression needed
samb1234
3. (Original post by thefatone)
samb1234
Double the compression. Energy stored in the spring is proportional to extension/compression squared, so for 4times the energy need 2 times the compression

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